The present invention relates to a device for producing heat by cogeneration comprising a heat source, a steam turbine and a condenser situated at the exhaust of the turbine.
Cogeneration consists in simultaneously producing electricity and heat from a steam turbine, a gas turbine or a heat engine.
On a steam turbine, the heat can be extracted in the form of steam, taken by steam outlet between two rows of fins of the rotor at a pressure which makes it possible to power a steam-water heat exchanger. The position of the steam outlet on the body of a turbine makes it possible to take a certain quantity of steam at a variable pressure level depending on the use of the steam. The heat produced by the steam-water exchanger is then used directly or indirectly to heat premises or for various industrial applications.
The steam taken at a turbine steam outlet reduces the production of electricity over the fraction of steam that does not leave via the exhaust of the turbine at close to vacuum pressure. The loss of electrical production depends on the flow rate and outlet pressure.
At the outlet of the turbine, the steam condenser is used to transform the steam from the gaseous phase to liquid phase (condensate), and allows for looping of the closed energy-transformation cycle by returning the condensates to the heat source.
The steam condensers are heat exchangers used to condense the steam, in the form of H2O gas, into liquid water. It will be recalled that, during the condensation of the steam, the latent heat of transformation of the gaseous phase to liquid phase releases a significant energy, called the latent heat of condensation. This condensation phenomenon is reversible, and the counterpart is the evaporation of the water. The steam/water condensers are heat exchangers widely used in the field of static or dynamic heating.
In thermodynamic applications, the condensers constitute the “cold” source of the closed cycle. Several types of condensers can be distinguished.
The air condenser is a condenser which uses as coolant the ambient air or a gas. The air passes through exchange bodies comprising fins and the flow of air is mechanical. Air condensers operate within a pressure range that is very slightly positive and often negative relative to atmospheric pressure.
The hydrocondenser is a condenser which uses as coolant water or a liquid solution. These appliances are used in thermal power plants, their high heat exchange capacity making it possible to improve the performance levels of the thermodynamic cycle. The water passes through an exchanger with tubular surface or with plates.
The condenser is engineered and configured to allow for the condensation of all the steam obtained from the turbine or from the desuperheated expansion of the steam produced by a steam generator. The coolant of the condenser takes away, in the form of heat, a significant quantity of energy which is dissipated into the natural environment (air or water) and consequently lost. In general, the energy dissipated by the condenser represents approximately 50% of the primary energy consumed.
WO 2005/119014 relates to an installation for jointly producing electrical energy and heat, for example for heating greenhouses. The steam leaving the low-pressure stage of a turbine is partly directed to an air condenser, and the rest is directed to a hydrocondenser. The arrangement of the various units has to be improved as much for the recovery of energy as for space occupancy.